Gigabit Passive Optical Network Transmission Convergence Extension for Next Generation Access

ABSTRACT

An apparatus comprising a data framer configured to frame a data stream into a plurality of frames each comprising a plurality of fields sized to align the frames with a word boundary greater than or equal to about four bytes long, and an optical transmitter coupled to the data framer and configured to transmit the frames. Included is an apparatus comprising at least one component configured to implement a method comprising encapsulating a data stream with at least one Gigabit Passive Optical Network (GPON) Encapsulation Method (GEM) payload aligned with a word boundary at least about four bytes long, encapsulating the GEM payload with a GPON Transmission Convergence (GTC) frame aligned with the word boundary, and transmitting the GTC frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 12/355,837 filed Jan. 19, 2009, which claims priority to U.S.Provisional Patent Application 61/046,474, filed Apr. 21, 2008 byYuanqiu Luo et al., and entitled “Gigabit Passive Optical NetworkTransmission Convergence Extension for Next Generation Access,” both ofwhich are incorporated herein by reference as if reproduced in itsentirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

A passive optical network (PON) is one system for providing networkaccess over “the last mile.” The PON is a point to multi-point networkcomprised of an optical line terminal (OLT) at the central office, anoptical distribution network (ODN), and a plurality of optical networkunits (ONUs) at the customer premises. In some PON systems, such asGigabit PON (GPON) systems, downstream data is broadcasted at about 2.5Gigabits per second (Gbps) while upstream data is transmitted at about1.25 Gbps. However, the bandwidth capability of the PON systems isexpected to increase as the demands for services increase. To meet theincreased demand in services, the logic devices in emerging PON systems,such as Next Generation Access (NGA), are being reconfigured totransport the data frames at higher bandwidths, for example at about tenGbps, and to support a larger number of ONUs.

SUMMARY

In one embodiment, the disclosure includes an apparatus comprising adata framer configured to frame a data stream into a plurality of frameseach comprising a plurality of fields sized to align the frames with aword boundary greater than or equal to about four bytes long, and anoptical transmitter coupled to the data framer and configured totransmit the frames.

In another embodiment, the disclosure includes an apparatus comprisingat least one component configured to implement a method comprisingencapsulating a data stream with at least one GPON Encapsulation Method(GEM) payload aligned with a word boundary at least about four byteslong, encapsulating the GEM payload with a GPON Transmission Convergence(GTC) frame aligned with the word boundary, and transmitting the GTCframe.

In yet another embodiment, the disclosure includes a method comprisingencapsulating a data stream into a plurality of fields, aligning thelengths of the fields individually or combined to a word boundary equalto at least about four bytes, packaging the fields into a frame, andtransmitting the frame.

These and other features will be more clearly understood from thefollowing detailed description taken in conjunction with theaccompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in connection with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 is a schematic diagram of an embodiment of a PON.

FIG. 2 is an illustration of an embodiment of a downstream GPONTransmission Convergence frame.

FIG. 3 is an illustration of an embodiment of an upstream GPONTransmission Convergence frame.

FIG. 4 is an illustration of an embodiment of a GPON EncapsulationMethod payload.

FIG. 5 is a flowchart of an embodiment of a framing method.

FIG. 6 is a schematic diagram of an embodiment of a general-purposecomputer system.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods may be implemented using any number oftechniques, whether currently known or in existence. The disclosureshould in no way be limited to the illustrative implementations,drawings, and techniques illustrated below, including the exemplarydesigns and implementations illustrated and described herein, but may bemodified within the scope of the appended claims along with their fullscope of equivalents.

Reconfiguring the PON system's logic to support higher transmissionrates or more ONUs may include modifying existing protocols, such as aGPON protocol as defined by the ITU-T G.984.3 standard, which isincorporated herein by reference. The GPON protocol comprises a GTClayer that defines the frames for encapsulating the data, such asEthernet frames or other packets. Disclosed herein is a system andmethod for extending the GTC layer of the GPON protocol for NGA. Theextended GTC layer may define a plurality of frames similar to the GTClayer of the GPON protocol, where at least some of the frames may bemodified to support higher bandwidth for NGA. Additionally, the modifiedframes may be used for transporting a larger number of data flows for alarger quantity of ONUs. The modified frames may comprise downstream GTCframes and upstream GTC frames, which may comprise network control andmanagement information and GEM payloads.

To support the increase in transmission rates, the length of the fieldsof the modified frames may be aligned with a similarly scaled wordboundary. For instance, if the transmission rates are increased aboutfour times, e.g., to about ten Gbps, the length of the fields of themodified frames may be aligned with about four times the word boundary,e.g., to about four bytes. Alternatively, the word boundary may be anyinteger multiple of about four bytes long. Accordingly, the GEM payloadsand other network control and management information may be encapsulatedinto frames comprising field lengths equal to integer multiples of aboutfour bytes. As such, the data may be encapsulated and de-capsulatedusing available electronic circuits with about the same performance orprocessing speed and without substantial upgrades or increase incomplexity. The increase in the length of the fields may also providemore addresses or identifiers to support more ONUs and more data flows.Additionally, at least some of the fields may be updated to deprecate ordisable Asynchronous Transfer Mode (ATM) functionality, which may not beused for NGA.

FIG. 1 illustrates one embodiment of a PON 100. The PON 100 comprises anOLT 110, a plurality of ONUs 120, and an ODN 130, which may be coupledto the OLT 110 and the ONUs 120. The PON 100 may be a communicationsnetwork that does not require any active components to distribute databetween the OLT 110 and the ONUs 120. Instead, the PON 100 may use thepassive optical components in the ODN 130 to distribute data between theOLT 110 and the ONUs 120. The PON 100 may be NGA systems, such as tenGbps GPONs (or XGPONs), which may have a downstream bandwidth of aboutten Gbps and an upstream bandwidth of at least about 2.5 Gbps. Otherexamples of suitable PONs 100 include the asynchronous transfer mode PON(APON) and the broadband PON (BPON) defined by the ITU-T G.983 standard,the GPON defined by the ITU-T G.984 standard, the Ethernet PON (EPON)defined by the IEEE 802.3ah standard, and the wavelength divisionmultiplexed (WDM) PON (WPON), all of which are incorporated herein byreference as if reproduced in their entirety.

In an embodiment, the OLT 110 may be any device that is configured tocommunicate with the ONUs 120 and another network (not shown).Specifically, the OLT 110 may act as an intermediary between the othernetwork and the ONUs 120. For instance, the OLT 110 may forward datareceived from the network to the ONUs 120, and forward data receivedfrom the ONUs 120 onto the other network. Although the specificconfiguration of the OLT 110 may vary depending on the type of PON 100,in an embodiment, the OLT 110 may comprise a transmitter and a receiver.When the other network is using a network protocol, such as Ethernet orSynchronous Optical Networking/Synchronous Digital Hierarchy(SONET/SDH), that is different from the PON protocol used in the PON100, the OLT 110 may comprise a converter that converts the networkprotocol into the PON protocol. The OLT 110 converter may also convertthe PON protocol into the network protocol. The OLT 110 may be typicallylocated at a central location, such as a central office, but may belocated at other locations as well.

In an embodiment, the ONUs 120 may be any devices that are configured tocommunicate with the OLT 110 and a customer or user (not shown).Specifically, the ONUs 120 may act as an intermediary between the OLT110 and the customer. For instance, the ONUs 120 may forward datareceived from the OLT 110 to the customer, and forward data receivedfrom the customer onto the OLT 110. Although the specific configurationof the ONUs 120 may vary depending on the type of PON 100, in anembodiment, the ONUs 120 may comprise an optical transmitter configuredto send optical signals to the OLT 110 and an optical receiverconfigured to receive optical signals from the OLT 110. Additionally,the ONUs 120 may comprise a converter that converts the optical signalinto electrical signals for the customer, such as signals in theEthernet or ATM protocol, and a second transmitter and/or receiver thatmay send and/or receive the electrical signals to a customer device. Insome embodiments, ONUs 120 and optical network terminals (ONTs) aresimilar, and thus the terms are used interchangeably herein. The ONUsmay be typically located at distributed locations, such as the customerpremises, but may be located at other locations as well.

In an embodiment, the ODN 130 may be a data distribution system, whichmay comprise optical fiber cables, couplers, splitters, distributors,and/or other equipment. In an embodiment, the optical fiber cables,couplers, splitters, distributors, and/or other equipment may be passiveoptical components. Specifically, the optical fiber cables, couplers,splitters, distributors, and/or other equipment may be components thatdo not require any power to distribute data signals between the OLT 110and the ONUs 120. Alternatively, the ODN 130 may comprise one or aplurality of processing equipment, such as optical amplifiers. The ODN130 may typically extend from the OLT 110 to the ONUs 120 in a branchingconfiguration as shown in FIG. 1, but may be alternatively configured inany other point-to-multi-point configuration.

In an embodiment, the OLT 110 and the ONUs 120 may comprise a dataframer, which may be coupled to the transmitter and/or the receiver.Specifically, the data framer may be any device configured to processthe data between the OLT 110 and the ONUs 120 by encapsulating the data,such as Ethernet data, into frames or decapsulating the data from theframes according to a PON protocol. For instance, the data framer may behardware, such as a processor, comprising electronic or logic circuitry,which may be designed for such purpose. Alternatively, the data framermay be software or a firmware, which may be programmed for such purpose.The PON protocol may be used by the OLT 110 and the ONUs 120 to exchangethe data, such as a GPON protocol defined by the ITU-T G.984.3 standard.The GPON protocol may comprise a GTC layer that provides a plurality offunctionalities, including media access control (MAC) functionalitiesfor data framing over upstream and downstream channels, a GEM forframing the data, and status reporting signaling using dynamic bandwidthallocation for upstream data.

In an embodiment, the GTC layer may define a word boundary, which mayrepresent a fixed logic block that aligns the data in the frames. Thedata framer may align the length of the data fields of the frames to theword boundary to avoid variable or odd length fields in the frames andhence variable or odd length logic blocks. Variable or odd length logicblocks may be undesirable because they may be more difficult to processusing the data framer at the OLT 110 or the ONUs 120. The word boundarymay be chosen based on the transmission rates of the system, such thatthe aligned data can be processed using available electronic circuitswith tolerable processing speeds or clock speeds. For example, in GPONsystems, the word boundary may be set to about one byte (about eightbits), and hence the length of the fields may be equal to integermultiples of about one byte.

To accommodate the higher data rates for NGA, the GTC layer of the GPONprotocol may be extended by increasing the word boundary based on theincreased bandwidth. Specifically, as the data rates increase, theavailable electronic circuits or logic circuitry may require higherclock speeds for processing and framing the data, which may not bepractical. However, when the word boundary is increased, more data perlogic block may be handled by such circuits, which may reduce the clockspeed requirement. Accordingly, the word boundary may be scaledproportionally to the increase in bandwidth to maintain about the sameprocessing speed requirement, which may be achieved by the availableelectronic circuits. For instance, to accommodate the higher data ratesfor NGA at about ten Gbps, which may be equal to about four times the2.5 Gbps rate, the word boundary of about one byte may be scaledproportionally by about four times. As such, the increased word boundaryin the extended GTC layer may be equal to about four bytes or about 32bits. In other embodiments, the increased word boundary may be greaterthan about four bytes, for example about eight bytes. Further, the framemay be aligned with the increased word boundary by increasing the lengthof the fields in the frames. The increased field lengths may also beused to accommodate more values, addresses, or identifiers to supportmore ONUs 120, more data flows, or both.

FIG. 2 illustrates an embodiment of a downstream GTC frame 200. Thedownstream GTC frame 200 may comprise downstream data transmitted fromthe OLT 110 to any of the ONUs 120, for instance over a downstreamchannel. For instance, the downstream GTC frame 200 may broadcasted bythe OLT 110 and comprise payload data as well as network control andmanagement information. Each ONU 120 may receive the downstream GTCframe 200 and identify the corresponding data assigned to the ONU 120using some addressing information, such as an ONU identifier (ONU-ID).The downstream GTC frame 200 may comprise a Physical Control Blockdownstream (PCBd) 210 and a Downstream Payload 220, which may be a GEMpayload as described below. The PCBd 210 may comprise a plurality offields, such as a Physical Synchronization (PSync) 211, anIdentification (Ident) 212, a Physical Layer Operations, Administrationand Maintenance (PLOAM) downstream or PLOAMd 213, a Bit InterleavedParity (BIP) 214, a Payload Length downstream (Plend) 215, and anUpstream Bandwidth map (US BWmap) 216.

The PSync 211 may comprise a fixed pattern that precedes the remainingfields in the PCBd 210. This pattern may be used at the ONUs 120, forinstance at the data framer coupled to the receiver, to detect thebeginning of the downstream GTC frame 200 and establish synchronization.For example, the PSync 211 may comprise the fixed pattern 0xB6AB31E0,which may not be scrambled. In the GTC layer of the GPON protocol, thelength of the PSync 211 may be equal to about four bytes, which mayalready be aligned and equal to about the increased word boundary tosupport a higher bandwidth in the GPON or NGA, e.g., about ten Gbpstransmission rates. Hence, no changes may be required for the PSync 211in the extended GTC layer.

The Ident 212 may comprise a counter to provide lower rate synchronousreference signals, which may be used by the ONU 120 with the PSync 211for synchronization purposes. For instance, similar to the PSync 211,the length of the Ident 212 in the GPON protocol may be equal to about32 bits, of which the first bit may be a forward error correction (FEC)bit, the second bit may be reserved, and the remaining and lesssignificant about 30 bits may comprise a counter that may be incrementedfor each next transmitted Ident 212. When the counter reaches apredetermined maximum value, the Ident 212 may be reset to zero on thenext downstream GTC frame 200. Similar to the PSync 211, since thelength of the Ident 212 may be aligned and equal to about the increasedword boundary, the Ident 212 may not be changed in the extended GTClayer.

The PLOAMd 213 may comprise a PLOAM message, which may be sent from theOLT 110 to the ONUs 120 and include Operations, Administration andMaintenance (OAM) related alarms or threshold-crossing alerts triggeredby system events. The PLOAMd 213 may comprise a plurality of sub-fields,such as an ONU-ID, a message identifier (Message-ID), a message data,and a Cyclic Redundancy Check (CRC). The ONU-ID may comprise an address,which may be assigned to one of the ONUs 120 and may be used by that ONU120 to detect its intended message. The Message-ID may indicate the typeof the PLOAM message and the message data may comprise the payload ofthe PLOAM message. The CRC may be used to verify the presence of errorsin the received PLOAM message. For instance, the PLOAM message may bediscarded when the CRC fails. To support the higher bandwidth in theGPON or NGA, the length of the PLOAMd 213 may be changed to an integermultiple of about four bytes long, for example about 16 bytes long,thereby aligning the data at about four bytes. Further, the length ofthe ONU-ID may be equal to about one byte, and hence may be used toindentify up to about 256 individual ONUs 120. In the extended GTClayer, the length of the ONU-ID may be increased to about four bytes toalign the data to the increased word boundary. Accordingly, the extendedONU-ID may be used to identify substantially more than 256 ONUs 120.Further, the format of the CRC, such as a CRC-8 format with generatorpolynomial (x⁸+x²+x+1), may be changed to account for at least some ofthe additional bits of the extended PLOAM message. Alternatively, thesame CRC format may be used, and hence the first bit in the PLOAMd 213,which may not be covered by the CRC format, may not be protected orconsidered for error detection.

The BIP 214 may comprise a bit interleaved parity of all the bytestransmitted since the last receive BIP 214. The bit interleaved paritymay also be calculated at the ONUs 120 and then compared to the bitinterleaved parity of the BIP 214 to measure the number of errors on thelink. The BIP 214 may be equal to about four bytes, which aligns it withthe increased word boundary in the extended GTC layer.

The Plend 215 may comprise a plurality of subfields, including a Blength (Blen) and a CRC. The Blen may indicate the length of the USBWmap 216, where the actual length of the US BWmap 216 in bytes may beequal to about eight times the value of Blen. The CRC may be configuredsubstantially similar to the CRC of the PLOAMd 213. In some systems thatsupport ATM communications, the subfields may also include an A length(Alen) subfield that indicates the length of an ATM payload, which maycomprise a portion of the downstream GTC frame 200. To disable ordeprecate ATM communications or functionality in the GPON or NGA, theAlen may be removed or discarded in the extended GTC layer. Tocompensate for the missing bits of the Alen and align the length of thePlend 215 to the increased word boundary, the length of the Blen, theCRC, or both may be adjusted to obtain a total length of about fourbytes for the Plend 215. For instance, the length of the CRC may beincreased, which also improves error detection.

The US BWmap 216 may comprise an array of blocks or subfields, each ofwhich may have a length of about eight bytes. Each block may comprise asingle bandwidth allocation to an individual Transmission Container(T-CONT), which may be used for managing upstream bandwidth allocationin the GTC layer. Specifically, the T-CONT may be a transport entity inthe GTC layer that may be configured to transfer higher-layerinformation from an input to an output, e.g., from the OLT 110 to any ofthe ONUs 120. Each block may comprise a plurality of subfields, such asan Allocation identifier (Alloc-ID), a Flags, a Start Time (SStart), aStop Time (SStop), and a CRC. Since the length of the US BWmap 216 maybe equal to an integer multiple of about eight bytes, the total lengthof the US BWmap 216 may already be aligned with the increased wordboundary, and hence may not be changed. However, the granularity of theUS BWmap 216 may be changed, for instance to about four bytes in eachblock.

FIG. 3 illustrates an embodiment of an upstream GTC frame 300. Theupstream GTC frame 300 may comprise upstream data transmitted from oneof the ONUs 120 to the OLT 110, including payload data and networkcontrol and management information, for instance over an upstreamchannel. The upstream GTC frame 300 may comprise a Physical LayerOverhead upstream (PLOu) 310, a PLOAM upstream (PLOAMu) 316, a DynamicBandwidth Report upstream (DBRu) 318, and an Upstream Payload 320, whichmay be a GEM payload as described below. The PLOu 310 may comprise aplurality of fields, such as a Preamble 311, a Delimiter 312, a BIP 313,an ONU-ID 314, and an Indication (Ind) 315. The upstream GTC frame 300may also comprise a Guard Time 305, which may precede the remainingfields and delineate the upstream GTC frame 300.

The combined fields of the PLOu 310 may indicate which ONU 120 may havesent the upstream GTC frame 300 to the OLT 110. For instance, thePreamble 311 and Delimiter 312 may correspond to that ONU 120 and may beformed as indicated by the OLT 110. The BIP 313 may comprise the bitinterleaved parity, as described above, and the ONU-ID 314 may comprisethe assigned address corresponding to the ONU 120. The Ind 315 mayindicate the status of the ONU 120 to the OLT 110, where the upstreamGTC frame 300 may be transmitted in substantially real time. In someinstances, the BIP 313, the ONU-ID 314, and the Ind 315 may not bealigned with the increased word boundary in the extended GTC layer.Hence, the length of the ONU-ID 314 may be about two bytes, and the BIP313 and the Ind 315 may be about one byte, thereby obtaining a totallength of about four bytes for the three fields, which may be suitable,for instance, for about ten Gbps transmission rates. Increasing thelength of the ONU-ID 314 may also provide more addresses that may beassigned to more ONUs 120, e.g., up to about 65,536 ONUs. In someembodiments, the lengths of the Preamble 311 and the Delimiter 312 mayalso be aligned individually or with the three remaining fields of thePLOu 310 to the increased word boundary.

Similar to the PLOAMd 213 of the downstream GTC frame 200, the PLOAMu316 may comprise a PLOAM message, which may be sent from the ONU 120 tothe OLT 110. The length of the PLOAMu 316 may be an integer multiple ofabout four bytes long, for example about 16 bytes long, in the extendedGTC layer. For instance, the length of the ONU-ID subfield of the PLOAMu316 may be increased to about two bytes. Further, the format of the CRCsubfield, e.g., CRC-8 format with generator polynomial (x⁸+x²+x+1), maynot be changed where the first bit in the PLOAMu 316 is not covered.

The DBRu 318 may comprise information that is related to the T-CONT. TheDBRu 318 may comprise two subfields, which may be a Dynamic BandwidthAssignment (DBA) and a CRC. The DBA may indicate a buffer occupancyreport, e.g., may comprise the traffic status of the T-CONT. In theextended GTC layer, the length of the DBRu may be matched to thegranularity of the US BWmap 216 of the downstream GTC frame 200, e.g.,at about four bytes. As such, the code points of Table 8-1 in ITU-TG.984.3 may be deprecated, replaced, or modified.

FIG. 4 illustrates an embodiment of a GEM payload 400. The GEM payload400 may comprise downstream data from the OLT 110 to the ONUs 120 orupstream data from an ONU 120 to the OLT 110. For instance, the GEMpayload 400 may correspond to the Downstream Payload 220 of thedownstream GTC frame 200 or the Upstream Payload 320 of the upstream GTCframe 300. The GEM payload 400 may comprise a Header 410 and a Payload420. The Header 410 may comprise a Payload Length Indicator (PLI) 411, aPort identifier (PortID) 412, a Payload Type Indicator (PTI) 413, and aHeader Error Control (HEC) 414.

The PLI 411 may indicate the length of the Payload 420 in bytes. The PLI411 may also indicate the beginning of the GEM payload 400. The lengthof the PLI 411 may be equal to about 12 bits, which may indicate aPayload 420 having a length up to about 4,095 bytes. The PortID 412 mayalso have a length equal to about 12 bits, which may provide up to about4,096 unique traffic identifiers. The traffic identifiers may correspondto a plurality of data flows, which may be multiplexed. The PTI 413 mayindicate the content type of the Payload 420. The length of the PTI 413may be equal to about three bits. The HEC 414 may provide errordetection and correction functions. For instance, the HEC 414 maycomprise about 12 bits of Bose and Ray-Chaudhuri (BCH) code, such as aBCH(39, 12, 2) code with a generator polynomial ofx¹²+x¹⁰+x⁸+x⁵+x⁴+x³+1, and a single parity bit.

In the extended GTC layer, the total length of the Header 410 may bealigned with the increased word boundary. Specifically, the Header 410may be an integer multiple of about four bytes long, for example abouteight bytes long. Accordingly, the length of the PLI 411, the PortID412, the PTI 413, the HEC 414, or combinations thereof may be increased.The length of the PLI 411 may be increased to indicate an extended GEMpayload 400 comprising more bytes and information. The length of thePortID 412 may be increased to provide more traffic identifierscorresponding to more multiplexed data flows. The length of the PTI 413may be increased to indicate more information about the Payload 420. Thelength of the HEC 414 may be increased to extend the BCH code to accountfor at least some of the additional bits of the extended Header 410, forinstance for about 63 bits of the Header 410 leaving a remaining paritybit unprotected.

The Payload 420 may comprise the payload data transported between theOLT 110 and the ONUs 120. The Payload 420 may also be extended andaligned with the increased word boundary. For instance, up to aboutthree padded bytes, e.g. null or zero value bytes, may be added to thePayload 420 to meet the word boundary alignment. If the Payload 420 isalready aligned with the increased word boundary, then no padded bytesmay be needed. The length of the Payload 420 and the padded bytes may beindicated using the PLI 411, the PTI 413, or both.

FIG. 5 illustrates one embodiment of a framing method 500, which may beused to encapsulate, transport, and de-capsulate data, such as Ethernetdata, in a PON system, such as the PON 100. The data may be transportedfrom the OLT 110 to the ONUs 120 or from one of the ONUs 120 to the OLT110. The data may correspond to a plurality of ONUs 120, a plurality ofdata flows, a plurality of T-CONTs, or combinations thereof. The framingmethod 500 may be implemented at the extended GTC layer of the GPONprotocol.

At block 510, the framing method 500 may frame the data to obtain analigned GEM payload, for instance using the data framer coupled to thetransmitter at the OLT 110 or the ONU 120. As such, the data may beencapsulated with other information in the format of a GEM payload, suchas the GEM payload 400. The other information may comprise the length ofthe data in bytes, the traffic identifiers of the data flows, the typeof the data, other information related to the data, or combinationsthereof. The GEM payload may then be aligned with the word boundarybased on the downstream bandwidth of the system, which may be about tenGbps. For instance, the data may be framed in an aligned payload portionof the GEM payload, such as the Payload 420, and the remaininginformation may be framed in an aligned header portion of the GEMpayload, such as the Header 410.

At block 520, the framing method 500 may frame the aligned GEM payloadto obtain an aligned GTC frame. Accordingly, the aligned GEM payload maybe encapsulated with other information in the format of a GTC frame,such as the downstream GTC frame 200 or the upstream GTC frame 300. Theother information may comprise a PLOAM message, the ONU-ID, bandwidthallocation for a T-CONT, other information related to the T-CONT, orcombinations thereof. The GTC frame may then be aligned with the wordboundary, which may be equal to about four bytes. For instance, thealigned GEM payload may be framed in a payload portion of the GTC frame,such as the Downstream Payload 220 or the Upstream Payload 320, and theremaining information may be framed in an aligned header portion of theGTC frame, such as the PCBd 210 or the PLOu 310.

At block 530, the framing method 500 may transport the aligned GTC framebetween the OLT 110 and the ONU(s) 120 via at least some of thecomponents of the PON system. For instance, the aligned GTC frame may betransported along the ODN 130 in a transparent manner without theknowledge of its data content. At block 540, the framing method 500 mayprocess the aligned GTC frame to obtain the aligned GEM payload in areverse manner of block 520, for instance using the data framer coupledto the receiver at the OLT 110 or the ONU 120. At block 550, the framingmethod 500 may process the aligned GEM payload to obtain the data in areverse manner of block 510.

The network components described above may be implemented on anygeneral-purpose network component, such as a computer or networkcomponent with sufficient processing power, memory resources, andnetwork throughput capability to handle the necessary workload placedupon it. FIG. 6 illustrates a typical, general-purpose network component600 suitable for implementing one or more embodiments of the componentsdisclosed herein. The network component 600 includes a processor 602(which may be referred to as a central processor unit or CPU) that is incommunication with memory devices including secondary storage 604, readonly memory (ROM) 606, random access memory (RAM) 608, input/output(I/0) devices 610, and network connectivity devices 612. The processor602 may be implemented as one or more CPU chips, or may be part of oneor more application specific integrated circuits (ASICs).

The secondary storage 604 is typically comprised of one or more diskdrives or tape drives and is used for non-volatile storage of data andas an over-flow data storage device if RAM 608 is not large enough tohold all working data. Secondary storage 604 may be used to storeprograms that are loaded into RAM 608 when such programs are selectedfor execution. The ROM 606 is used to store instructions and perhapsdata that are read during program execution. ROM 606 is a non-volatilememory device that typically has a small memory capacity relative to thelarger memory capacity of secondary storage 604. The RAM 608 is used tostore volatile data and perhaps to store instructions. Access to bothROM 606 and RAM 608 is typically faster than to secondary storage 604.

At least one embodiment is disclosed and variations, combinations,and/or modifications of the embodiment(s) and/or features of theembodiment(s) made by a person having ordinary skill in the art arewithin the scope of the disclosure. Alternative embodiments that resultfrom combining, integrating, and/or omitting features of theembodiment(s) are also within the scope of the disclosure. Wherenumerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example,whenever a numerical range with a lower limit, R_(l), and an upperlimit, R_(u), is disclosed, any number falling within the range isspecifically disclosed. In particular, the following numbers within therange are specifically disclosed: R=R_(l)+k*(R_(u)−R_(l)), wherein k isa variable ranging from 1 percent to 100 percent with a 1 percentincrement, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent,96 percent, 97 percent, 98 percent, 99 percent, or 100 percent.Moreover, any numerical range defined by two R numbers as defined in theabove is also specifically disclosed. Use of the term “optionally” withrespect to any element of a claim means that the element is required, oralternatively, the element is not required, both alternatives beingwithin the scope of the claim. Use of broader terms such as comprises,includes, and having should be understood to provide support fornarrower terms such as consisting of, consisting essentially of, andcomprised substantially of. Accordingly, the scope of protection is notlimited by the description set out above but is defined by the claimsthat follow, that scope including all equivalents of the subject matterof the claims. Each and every claim is incorporated as furtherdisclosure into the specification and the claims are embodiment(s) ofthe present disclosure. The discussion of a reference in the disclosureis not an admission that it is prior art, especially any reference thathas a publication date after the priority date of this application. Thedisclosure of all patents, patent applications, and publications citedin the disclosure are hereby incorporated by reference, to the extentthat they provide exemplary, procedural, or other details supplementaryto the disclosure.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods might beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein. For example, the variouselements or components may be combined or integrated in another systemor certain features may be omitted, or not implemented.

In addition, techniques, systems, subsystems, and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by one skilled in theart and could be made without departing from the spirit and scopedisclosed herein.

What is claimed is:
 1. An apparatus comprising: a data framer configuredto frame a data stream into a plurality of frames each comprising aplurality of fields sized to align the frames with a word boundarygreater than or equal to about four bytes long; and an opticaltransmitter coupled to the data framer and configured to transmit theframes.
 2. The apparatus of claim 1, wherein the word boundary length isbased on a transmission bandwidth, and wherein the word boundaryincreases proportionally with the transmission bandwidth.
 3. Theapparatus of claim 2, wherein the frames support identification of up toabout 65,536 unique optical network unit (ONU) addresses.
 4. Theapparatus of claim 1 further comprising an optical receiver coupled tothe data framer and configured to receive a plurality of second framescomprising a plurality of second fields each sized to align the secondframes with the word boundary, wherein the data framer is configured toobtain a second data stream from the second frames.
 5. The apparatus ofclaim 1, wherein the frames comprise a Gigabit Passive Optical Network(GPON) Transmission Convergence (GTC) frame.
 6. The apparatus of claim5, wherein the GTC frame comprises a Physical Control Block downstream(PCBd).
 7. The apparatus of claim 6, wherein the PCBd comprises aPhysical Synchronization (PSync), an Identification (Ident), a PhysicalLayer Operations, Administration and Maintenance downstream (PLOAMd), aBit Interleaved Parity (BIP), a Payload Length Downstream (Plend), andan upstream Bandwidth map (US BWmap).
 8. The apparatus of claim 7,wherein the PLOAMd is an integer multiple of about four bytes long, theBIP is about four bytes long, and the US BWmap is about four bytes long.9. A method comprising: framing a data stream into a plurality of frameseach comprising a plurality of fields sized to align the frames with aword boundary greater than or equal to about four bytes long; andtransmitting the frames.
 10. The method of claim 9, wherein framing thedata stream comprises: encapsulating the data stream into a plurality offields; aligning the lengths of the fields individually or combined to aword boundary equal to at least four bytes; and packaging the fieldsinto a frame.
 11. The method of claim 9, wherein the word boundarylength is based on a transmission bandwidth, and wherein the wordboundary increases proportionally with the transmission bandwidth. 12.The method of claim 11, wherein the frames support identification of upto about 65,536 unique optical network unit (ONU) addresses.
 13. Themethod of claim 9, further comprising receiving a plurality of secondframes comprising a plurality of second fields each sized to align thesecond frames with the word boundary, wherein the data framer isconfigured to obtain a second data stream from the second frames. 14.The method of claim 9, wherein the frames comprise a Gigabit PassiveOptical Network (GPON) Transmission Convergence (GTC) frame.
 15. Themethod of claim 14, wherein the GTC frame comprises a Physical ControlBlock downstream (PCBd).
 16. The method of claim 15, wherein the PCBdcomprises a Physical Synchronization (PSync), an Identification (Ident),a Physical Layer Operations, Administration and Maintenance downstream(PLOAMd), a Bit Interleaved Parity (BIP), a Payload Length Downstream(Plend), and an upstream Bandwidth map (US BWmap).
 17. The method ofclaim 16, wherein the PLOAMd is an integer multiple of about four byteslong, the BIP is about four bytes long, and the US BWmap is about fourbytes long.
 18. A method for framing data, comprising: encapsulating adata stream into at least one Gigabit Passive Optical Network (GPON)encapsulation Method (GEM) frame; and encapsulating the GEM frame into aGPON Transmission Convergence (GTC) frame; and transmitting the GTCframe, wherein the GEM frame comprises a header aligned with a wordboundary of an integer multiple of four bytes.
 19. The method of claim18, wherein the GTC frame comprises network control and managementinformation aligned with the word boundary of an integer multiple offour bytes.